From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH 1 of 3 v4/leftover] libxl: enable automatic
 placement of guests on NUMA nodes
Date: Tue, 17 Jul 2012 16:59:15 +0100
Message-ID: <1342540755.16704.11.camel@zakaz.uk.xensource.com>
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To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Andre Przywara <andre.przywara@amd.com>, Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>, George Dunlap <George.Dunlap@eu.citrix.com>, Juergen Gross <juergen.gross@ts.fujitsu.com>, xen-devel <xen-devel@lists.xen.org>, Dario Faggioli <raistlin@linux.it>
List-Id: xen-devel@lists.xenproject.org

On Tue, 2012-07-17 at 16:55 +0100, Ian Jackson wrote:

> > +/* Subtract two values and translate the result in [0, 1] */
> > +static double normalized_diff(double a, double b)
> > +{
> > +#define max(a, b) (a > b ? a : b)
> > +    if (!a && a == b)
> > +        return 0.0;
> > +    return (a - b) / max(a, b);
> > +}
> 
> 1. This macro max() should be in libxl_internal.h.
> 2. It should be MAX so people are warned it's a macro
> 3. It should have all the necessary ()s for macro precedence safety

You probably also want to do the necessary tricks to avoid multiple
evaluation of the arguments?